Atrial fibrillation (AF), the most common sustained arrhythmia in the population, imposes a large and growing burden on patients and the health care system alike. This rhythm is associated with substantial morbidity and impairment in health-related quality of life for many of the over 2 million U.S. citizens who suffer from it, leading to the development of aggressive techniques for eliminating its occurrence or palliating its effects. Electrical isolation of the pulmonary veins from the left atrium with radiofrequency catheter ablation has recently emerged as an important new therapy for AF. Promising early results with these techniques have generated considerable enthusiasm for the ablation approach, such that many centers are now offering it as standard therapy despite the current lack of prospective randomized data addressing its safety and efficacy. The proposed research plan has the overall goal of developing a cost-effectiveness model for comparing AF ablation with alternative therapeutic strategies. The data generated will be useful for physicians and patients who must make decisions about these therapies in the face of imperfect information. Several preliminary steps will be needed in order to develop a robust cost-effectiveness model in this area. Chief among these will be to develop a better understanding of the determinants of quality of life and health care resource utlization in the AF population.These questions will be addressed through analysis of an ongoing 1000 patient national registry of new onset AF patients. In addition, the utility weights needed to calculate quality adjusted life years (QALYs) - the preferred unit of effectiveness in cost-effectiveness analysis - have never been measured. Thus, procedural costs, quality of life, and utilities will be measured prospectively in patients undergoing AF ablation. Once all of this data is collected, the necessary inputs will combined in a Markov model comparing AF ablation with antiarrhythmic drug therapy, and atrio-ventricular junctional ablation with pacemaker implantation.